Electrode-cover for electric furnaces.



J. L. K. SNYDER. ELECTRODE COVER FOR ELECTRIC FURNACES.

APPLIGATION FILED SEPT. 5, 1911.

Patented Nov. 28, 1911.

iffy/F6011 1 2 UNITED STATES PATENT ormcn.

JOSEPH L. K. SNYDER, OF CLEVELAND, OHIO, vASSIGNOR TO NATIONAL CARBONCOMPANY, OF CLEVELAND, OHIO, A CORPORATION OF NEW JERSEY.

ELECTRODE-COVER FOR ELECTRIC FURNACES.

To all whom it may concern:

Be it known that I, JosErH L. K. SNYDER, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented a certain new and useful Improvement in Electrode- Covers forElectric Furnaces, of which the following is a full, clear, and exactdescription.

This invention relates to electric furnaces and the object is to providea furnace, the cover for which, forms at least one of the electrodes forintroducing the electric current within the furnace.

Generally speaking, the invention comprises the elements andcombinations thereof set forth in the accompanying claims.

Reference should be had to the accompanying drawings forming a part ofthis specification which show one form that the invention may assume.

Figure 1 is a sectional elevation of a furnace using a single phasecurrent and embodying my invention; and Fig. 2 is a sectional elevationof a furnace employing a three-phase current and showing my inventionapplied thereto.

In the furnace shown in Fig. 1, the body of the furnace is representedat A and'the vertical side walls thereof at A. It will be understoodthat the body, as well as the side walls of the furnace are made ofsuitable refractory material, and in addition, such material as willform a good insulation against loss of heat by radiation.

The hearth of the furnace is represented at B and is formed of suitablerefractory material. A tapping hole or opening is indicated at C, whichis of the usual construc tion.

One of the electrodes with which the furnace is provided is indicated atD, and the electric current is conducted to the same through theconducting agent I). This construction is such as is ordinarily used inelectric furnaces.

The cover E is of such proportions that it fits between the walls A andat the same time may easily be moved up and down within the spacebetween the walls. In length, the cover is terminated by the end wallsof the furnace. This cover is formed of some material or mixture ofmaterials Specification of Letters Patent.

Application filed September 5, 1911.

Serial No. 647,465.

which roduce a cover that will conduct electricity and at the sametimewill be highly refractory. The material most completely filling therequirements enumerated, is carbon or carbon mixed in suitableproportions with some such material as carborundum or alundum, orsimilar sub stances. The cover may conveniently be formed in a mold inwhich is placed granular carbon mixed with a suitable binder, the samebeing tamped to form a compact structure which is subsequently removedfrom the mold and baked.

The cover is suspended upo'n flexible hangers F by means of suitableclamps G which engage with a projecting portion E of the cover. Thisconstruction is but suggestive and other structures may be used whichwill accomplish the same purpose.

It will be apparent that the cover may be adjusted with respect to itsheight above the hearth of the furnace by increasing or diminishing thelength of the flexible members F. i

The current is conducted to the cover E by means of the conductor H andterminal member I, which latter member is securely fastened to the coverE so as to make good electrical contact therewith.

In Fig. 2 there is shown a type of furnace employing a three-phasecurrent and in this connection, the furnace may be provided with a coverhaving three sections represented at J, K and L, each section beingseparated from its adjacent section by means of an insulating wall ofrefractory material, such as is represented at M. These cover sectionsare likewise suspended upon flexible members, the 'same as is indicatedin Fig. 1, and the current may be introduced into each section in amanner similar to that shown in Fig. 1, and each of the sections iselectrically connected to one of the three wires of a three wire circuitcarrying a three-phase current. This furnace is but one form which afurnace embodying the principle of this invention and using athree-phase current may assume, and it will be understood that the coverelectrode idea .may be worked out in connection with any polyphasecurrent it is desired to use.

ln each form of the furnace shown, the cover is maintained above thebath in the Patented Nov. 28, 1911.

furnace a distance only sufficient for the maintenance of the are, itbeing understood that the arc is formed between the electrode cover andthe bath of materials which are being acted upon.

Suitable mechanism will be provided to maintain the covers at the properdistance from the bath of material within the furnace to maintain thearc. However, this mechanism forms no part of the invention, and is notshown.

In the ordinary electric furnace, the cover is maintained at somedistance above the surface of the material being treated and this isnecessarily so because the cover although composed of refractorymaterial will nevertheless be melted if the cover is brought too near tothe surface of the molten bath within the furnace. tances at whichcovers for electric furnaces are customarily placed, the inside of thecover usually melts and flows somewhat and must frequently be renewed.Hence, there is of necessity a certain dead space which must be heatedand the heat passing through this space and being again reflected uponthe bath loses its intensity because of the distance through which itmust pass.

A furnace of the present invention may have the cover as near thesurface of the bath as is possible without touching it, for carbon orcarbon mixed with such substances as indicated is substantially aperfectly refractory material and the most intense heat which might bedeveloped in the furnace would not be sufiicent to cause even a flowingof the material of which the cover is composed. It will thus be apparentthat the space between the cover and the bath becomes a'minimum and theheat developed by the current flow is all confined within acomparatively small space and hence accomplishes its maximum usefulness.It should further be noted that in the usual electric furnace employingthe ordinary electrodes, these electrodes become spindling or pointedupon that end which is adjacent the material within the furnace. This isobjectionable, inasmuch as it reduces the area of the electrode which isadjacent the furnace bath and by so much restricts the area of the bathover which the arc may play as it travels upon the face of the electrodewhich is adjacent the bath. As the electrode becomes more spindling, itwill eventually confine the arc to substantially a single spot, thusreducing the area of the bath in the furnace directly affected by thearc and by so much reducing the efficiency of the furnace.

The electrode cover of this invention being so near to the surface ofthe bath within the furnace, as has before been said, provides only asmall space between the bath and the electrode cover, and the atmospherewithin this space will be substantially reducing.

Even at the dis Hence, the electrode will not be consumed at least withany such rapidity as is the case with electrodes as at presentconstructed and used. Therefore, the cover electrode will presentsubstantially the same area to the surface of the bath within thefurnace at the end of a given operation as at the beginning thereof. Afurther advantage is obtained by the use of the cover electrode hereproposed, due to the fact that the electrode cover is of as great area,as the bath being treated. Hence, the are traveling as it does over allthe surface of the cover electrode which is opposite or adjacent thematerials in the furnace, will directly and successively act upondifferent portions of the material being treated, and in fact will inthe course of the treatment of a given bath of material play oversubstantially the entire surface thereof, and hence the distribution ofheat will be substantially uniform throughout the material treated. Aswill be apparent, this result is highly desirable, and it cannot beobtained in the furnaces using the ordinary electrodes.

\Vhile the electrode covers thus far described have been shown as madeentirely of a given material or mixture of materials, it is to beunderstood that it is entirely within the scope of my invention to haveonly the lower portion, or that portion which is adjacent the materialbeing treated, made of conducting material, and the upper portion may,if desired, be made of suitable refractory material, and furthersuitable heat insulating material may be employed in connection with thecover to prevent the radiation of heat as much as possible. Such a coveris shown in Fig. 8, the conducting portion being indicated at N and theother part of the electrode at O. The electric current is conducted tothe portion N of the cover through the plate P and pins Q. This cover isused in a furnace in the same manner as indicated in Figs. 1 and 2.Therefore, where in this specification and claims I speak of the coveras being of conducting material or of carbon or a mixture of carbon withother materials, it is intended to include all forms of the cover hereinshown and described.

Having thus described my invention, what I claim is:

1. The combination with an electric furnace of the arc type, of anelectric current conducting cover therefor, and means for conducting anelectric current thereto whereby the cover forms at least one of theelectrodes for the furnace.

2. The combination with an electric furnace, of an electric currentconducting cover therefor, said cover being adjustable with respect tothe furnace, and means for leading an electric current to said cover.

3. The combination with an electric furmace of the arc type, of a covertherefor, said posed of conducting material, and means for 10 coverbeing adapted to conduct an electric leading an electric current to thecover. current, that portion of the cover which is In testimony whereof,I hereunto efiix my toward the material Within the furnace besignaturein the presence of two Witnesses.

ing composed substantially of carbon.

4. The combination with an electric fur- JOSEPII SN YDEB" mice of theare type,- of a cover therefor, that Witnesses:

portion of the cover which is toward the ma RICHARD H. HAEVEY,

terial Within the furnace, at least being com- L. O. BROOKE.

